package com.pi2e.view.widget;


	import com.pi2e.R;

import android.content.Context;  
import android.graphics.Bitmap;  
import android.graphics.BitmapFactory;  
import android.graphics.Canvas;  
import android.graphics.Paint;  
import android.graphics.PorterDuff.Mode;  
import android.graphics.PorterDuffXfermode;  
import android.graphics.Rect;  
import android.graphics.RectF;  
import android.util.AttributeSet;  
import android.view.MotionEvent;  
import android.view.View;  
	  
	public class SwitchButton extends View implements android.view.View.OnClickListener{  
	    private Bitmap mSwitchBottom, mSwitchThumb, mSwitchFrame, mSwitchMask;  
	    private float mCurrentX = 0;  
	    private boolean mSwitchOn = true;//开关默认是开着的  
	    private int mMoveLength;//最大移动距离  
	    private float mLastX = 0;//第一次按下的有效区域  
	      
	    private Rect mDest = null;//绘制的目标区域大小  
	    private Rect mSrc = null;//截取源图片的大小  
	    private int mDeltX = 0;//移动的偏移量  
	    private Paint mPaint = null;  
	    private OnChangeListener mListener = null;  
	    private boolean mFlag = false;  
	  
	    public SwitchButton(Context context) {  
	        this(context, null);  
	        // TODO Auto-generated constructor stub  
	    }  
	  
	    public SwitchButton(Context context, AttributeSet attrs) {  
	        this(context, attrs, 0);  
	        // TODO Auto-generated constructor stub  
	    }  
	  
	    public SwitchButton(Context context, AttributeSet attrs, int defStyle) {  
	        super(context, attrs, defStyle);  
	        // TODO Auto-generated constructor stub  
	        init();  
	    }  
	  
	    /** 
	     * 初始化相关资源 
	     */  
	    public void init() {  
	        mSwitchBottom = BitmapFactory.decodeResource(getResources(),  
	                R.drawable.icon_netset_switch_bg_btn_on);  
	        mSwitchThumb = BitmapFactory.decodeResource(getResources(),  
	                R.drawable.icon_netset_swith_btn_on_ersi);  
	        mSwitchFrame = BitmapFactory.decodeResource(getResources(),  
	                R.drawable.icon_netset_switch_bg_btn_off);  
	        mSwitchMask = BitmapFactory.decodeResource(getResources(),  
	                R.drawable.icon_netset_switch_bg_btn_off);  
	        setOnClickListener(this);  
	        setOnTouchListener(new OnTouchListener() {  
	              
	            @Override  
	            public boolean onTouch(View v, MotionEvent event) {  
	                // TODO Auto-generated method stub  
	                return false;  
	            }  
	        });  
	          
	        mMoveLength = mSwitchBottom.getWidth() - mSwitchFrame.getWidth();  
	        mDest = new Rect(0, 0, mSwitchFrame.getWidth(), mSwitchFrame.getHeight());  
	        mSrc = new Rect();  
	        mPaint = new Paint();  
	        mPaint.setAntiAlias(true);  
	        mPaint.setAlpha(255);  
	        mPaint.setXfermode(new PorterDuffXfermode(Mode.DST_IN));  
	    }  
	  
	    @Override  
	    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {  
	        // TODO Auto-generated method stub  
	        setMeasuredDimension(mSwitchFrame.getWidth(), mSwitchFrame.getHeight());  
	    }  
	  
	    @Override  
	    protected void onDraw(Canvas canvas) {  
	        // TODO Auto-generated method stub  
	        super.onDraw(canvas);  
	        if (mDeltX > 0 || mDeltX == 0 && mSwitchOn) {  
	            if(mSrc != null) {  
	                mSrc.set(mMoveLength - mDeltX, 0, mSwitchBottom.getWidth()  
	                    - mDeltX, mSwitchFrame.getHeight());  
	            }   
	        } else if(mDeltX < 0 || mDeltX == 0 && !mSwitchOn){  
	            if(mSrc != null) {  
	                mSrc.set(-mDeltX, 0, mSwitchFrame.getWidth() - mDeltX,  
	                    mSwitchFrame.getHeight());  
	            }  
	        }   
	/*<span style="white-space:pre">        </span>//这儿是离屏缓冲，自己感觉类似双缓冲机制吧  
*/	        int count = canvas.saveLayer(new RectF(mDest), null, Canvas.MATRIX_SAVE_FLAG  
	                | Canvas.CLIP_SAVE_FLAG | Canvas.HAS_ALPHA_LAYER_SAVE_FLAG  
	                | Canvas.FULL_COLOR_LAYER_SAVE_FLAG  
	                | Canvas.CLIP_TO_LAYER_SAVE_FLAG);  
	  
	        canvas.drawBitmap(mSwitchBottom, mSrc, mDest, null);  
	        canvas.drawBitmap(mSwitchThumb, mSrc, mDest, null);  
	        canvas.drawBitmap(mSwitchFrame, 0, 0, null);  
	        canvas.drawBitmap(mSwitchMask, 0, 0, mPaint);  
	        canvas.restoreToCount(count);  
	    }  
	      
	    @Override  
	    public boolean onTouchEvent(MotionEvent event) {  
	        // TODO Auto-generated method stub  
	        switch (event.getAction()) {  
	        case MotionEvent.ACTION_DOWN:  
	            mLastX = event.getX();  
	            break;  
	        case MotionEvent.ACTION_MOVE:  
	            mCurrentX = event.getX();  
	            mDeltX = (int) (mCurrentX - mLastX);  
	            // 如果开关开着向左滑动，或者开关关着向右滑动（这时候是不需要处理的）  
	            if ((mSwitchOn && mDeltX < 0) || (!mSwitchOn && mDeltX > 0)) {  
	                mFlag = true;  
	                mDeltX = 0;  
	            }  
	              
	            if (Math.abs(mDeltX) > mMoveLength) {  
	                mDeltX = mDeltX > 0 ? mMoveLength : - mMoveLength;  
	            }  
	            invalidate();  
	            return true;  
	        case MotionEvent.ACTION_UP:  
	            if (Math.abs(mDeltX) > 0 && Math.abs(mDeltX) < mMoveLength / 2) {  
	                mDeltX = 0;  
	                invalidate();  
	                return true;  
	            } else if (Math.abs(mDeltX) > mMoveLength / 2 && Math.abs(mDeltX) <= mMoveLength) {  
	                mDeltX = mDeltX > 0 ? mMoveLength : -mMoveLength;  
	                mSwitchOn = !mSwitchOn;  
	                if(mListener != null) {  
	                    mListener.onChange(this, mSwitchOn);  
	                }  
	                invalidate();  
	                mDeltX = 0;  
	                return true;  
	            } else if(mDeltX == 0 && mFlag) {  
	                //这时候得到的是不需要进行处理的，因为已经move过了  
	                mDeltX = 0;  
	                mFlag = false;  
	                return true;  
	            }  
	            return super.onTouchEvent(event);  
	        default:  
	            break;  
	        }  
	        invalidate();  
	        return super.onTouchEvent(event);  
	    }  
	      
	    public void setOnChangeListener(OnChangeListener listener) {  
	        mListener = listener;  
	    }  
	      
	    public interface OnChangeListener {  
	        public void onChange(SwitchButton sb, boolean state);  
	    }  
	  
	    @Override  
	    public void onClick(View v) {  
	        // TODO Auto-generated method stub  
	        mDeltX = mSwitchOn ? mMoveLength : -mMoveLength;  
	        mSwitchOn = !mSwitchOn;  
	        if(mListener != null) {  
	            mListener.onChange(this, mSwitchOn);  
	        }  
	        invalidate();  
	        mDeltX = 0;  
	    }  
	
}
